Flight attendants say this is the biggest misconception about the job

Your interactions with flight attendants may have been limited to asking for a Diet Coke or a bag of pretzels, but there's a lot more to the job than serving passengers.

"A lot of people think we're their waiters and that we're there to make sure they get drinks and food, but they don't realize that we're there to actually save their lives in case something happens," Delta flight attendant Niguel Modeste told me when I spent a day on board with him and the rest of his crew.

His co-worker Melissa Pittman added: "The biggest misconception ever is the fact that people think we're glorified waitresses, when in reality, you start having a heart attack or you have a medical event on the aircraft — the first person you're going to look for is a flight attendant because we know what to do. We're trained on what to do."

Melissa Pittman

CNBC Make It

She's referring to the eight-week training program that all Delta flight attendants have to complete in order to earn their wings. The program includes medical and first-aid training, during which they learn how to use an automated external defibrillator and how to perform CPR.

Medical crises are going to happen on board at some point during their career. In fact, they happen "more than you think," another member of the crew, Sarah Motter, told me. "We have to be prepared for anything."

That's part of the reason Delta is so selective when hiring. Of the hundreds of thousands of people who apply to be a Delta flight attendant each year, less than 1 percent make the cut.

While a large chunk of each flight is spent attending to passengers, preparing meals and serving drinks, Pittman says, "our first job — our priority on that aircraft — is getting you to your destination safely."